RESUMO
This work presents the results of a DNA test aimed to determine a possible biological link of paternal half brotherhood of two males. The combined use of biparentally inherited markers (autosomal STRs) and a panel of 27 Y-STRs allowed us to determine the existence of a biological relationship of kinship, even after detecting three mutations at their Y-STR haplotypes along the analyses, constituting an infrequent multiple mutation situation. This case is an example illustrating the importance of having different analytical markers sets and strategies for clarifying complex kinship cases where mutations occur.
Assuntos
Repetições de Microssatélites , Irmãos , Masculino , Humanos , Haplótipos , Genótipo , Cromossomos Humanos Y , Mutação , Impressões Digitais de DNA , Genética PopulacionalRESUMO
Chimerism testing by short tandem repeats (STRs) is used to monitor engraftment after allogeneic hematopoietic stem cell transplantation (HSCT). Generally, STR alleles are stable and transferred from parent to child or from donor to recipient. However, 3 cases did not follow this norm. Additional work-up with help from forensic literature solved these mysteries. In case 1, the patient received HSCT from his son. The son shared STR alleles in 22/23 loci except Penta E, which was explained by repeat expansion in the son. In case 2, the patient had been in remission for 14 years after HSCT for lymphoma and developed repeat expansion in CSF1PO in granulocytes. In case 3, a pre-HSCT patient demonstrated 3 alleles, with 2 peaks taller than the third, in the FGA locus (chromosome 4). A combination of a triallelic variant and leukemia-associated trisomy 4 explained the finding. STR number variants are rare and clinically inconsequential but can overlap malignancy-associated, clinically significant changes.